U.S. Pat. No. 6,705,630 describes a human powered wheeled transportation device that uses wheel skates each encircling the foot of the user during use. Each of the wheel skates has a respective wheel, an inner circular rim and an outer circular rim spaced from the inner circular rim by bearings. The inner circular rim supports a foot placement platform. A pivot link extends between the inner circular rims of two wheel skates to connect them together. Such has the effect of constraining the foot placement platform against moving relative to the frame so as to keep the inner circular rims and thereby the foot placement platforms stationary. The pivot link enables the user to keep just one foot in one of the foot placement platforms while resting the other foot on the frame if desired.
U.S. Pat. No. 7,059,613 also describes a human powered wheeled transportation device that that permits independent foot movement with two small wheels provided under a user's foot. However, no wheel encircles the user's foot.
U.S. Pat. No. 7,980,568, by the present inventor, describes a human powered wheeled transportation device that encircles the foot of the user during use and yet provided for independent foot movement.
These types of devices are commonly operated by moving one's feet in oscillating “wave” motion. Since this method can be difficult to learn, a need exists for learning aids such as a means for limiting the wheels to moving in only one direction (to help the user propel himself in that direction), and a means for maintaining the distance between the user's feet in an optimal range.
It would also be beneficial to have a means for making the two wheel skate devices more convenient to carry or stow together.